Electric motor



E. L. HALL ELECTRIC MOTOR Filed Oct. 13, 1955 E A V H m L VI R E M E United States Patent ELECTRIC MOTOR Emery L. Hall, Hinsdale, Ill., assignor, by mesne assignments, to Whirlpool Corporation, a corporation of Delaware Application October 13, 1955, Serial No. 540,191

1 Claim. (Cl. 310246) This invention relates to electric motors and, more particularly, to a brush holder therefor.

The improved brush holder of this invention employs a coil spring of small radius having the coil or volute portion bearing against one end of the brush to urge it toward the motors commutator. The spring includes a flat, elongated spring metal strip having the outer end anchored with the other end coiled into a self-rewinding volute. This volute bears against the end of the brush that is opposite to the commutator to urge the brush toward the commutator. Thus, the spring keeps the brush in contact with the commutator as the brush wears away. In such a holder, the brush must be replaced from time to time due to wear. In the past such replacement required removal of the entire brush holder from its mounting on the motor, as the brush could only be removed from the commutator end of the brush holder. This was laborious and timeconsuming.

The brush holder of this invention successfully solves the above problem of providing substantially uniform pressure on the brush yet permitting easy replacement of the brush. In this invention the brush holder is constructed with a removable base member. The coil spring is attached to this base member and means are provided for removably locking the base member in the holder. Thus, when a worn brush must be replaced, it is not necessary to remove the entire holder from its mounting. All that need be done is to release the base member and remove it and the worn brush. The new brush is then inserted and the base member replaced or both may be inserted simultaneously.

The brush holder of this invention Will be described as related to the embodiment shown in the accompanying drawings. Of the drawings:

Fig. l is a sectional view through a brush holder of this invention taken substantially along line 11 of Fig. 2.

Fig. 2 is a sectional view taken substantially along line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken substantially along line 33 of Fig. 1.

The brush holder of this invention comprises an elongated casing open at its opposite ends in which is positioned a brush 11 to make contact with a commutator 12 shown in part diagrammatically in Fig. 2. A pigtail connection 13 of copper wire or the like is attached to the brush 11 by any means desired. One side of the casing 10 has a raised portion 15 which defines a channel extending from end to end of the casing in which the connection 13 is located. A coil spring 16 is provided comprising a flat, elongated metal strip 17 secured at its outer end to a movable base member 18 as by a rivet 19. This sheet metal base member is normally located on the interior of the casing 10 on the side opposite to the channel 15. The other end of the spring 16 is coiled into a selfrewinding volute 20. This volute bears against the end of the brush 11 opposite to the commutator 12 and thus urges the brush toward the commutator.

g 2,851,622 Patented Sept. 9, 1958 The movable base member 18 is positioned in thecasing 10 on one side of the brush in a slot 21 as shown in Fig. 3. This slot is defined on its outer side by a side 25 of the casing 10 which is bent to form the slot. The base member 18 and the attached spring 16 may be removed from the casing 10 by sliding it out of the slot 21 to the right as viewed in Figs. 1 and 2.

The movable base member 18 is normally held in position in the casing 10 by means of a metal clip 22. The clip 22 is secured to the casing 10 at the commutator end by a rivet 23 and is mounted on an outwardly-extending central part 25a of the casing side 25. The clip 22 tends to remain in the position shown in Fig. 2 because of the spring-like quality of its long arm 22a. The clip 22 is provided with atab 24. By applying a downward force on the tab 24 clip 22 will be deflected in a downward direction, thus, clearing the barrier part 22b of the clip from the movable base member 18 so that the base member, spring 16 and worn brush 11 may be removed through the end of the casing 10 that is opposite to the commutator. If the worn brush fails to come out readily after the base plate 18 has been removed, it may easily be withdrawn by using the pigtail connection 13 to pull it free. A new brush 11 is inserted and the movable base member 18 is slid back into the casing 10. If desired, the

new brush and base member may be inserted simultaneously. The clip 22, when released, springs back to the locked position to hold the base member and thus the spring and brush in position as shown in the drawings.

The side 25 of the casing 10 is also provided with an extended flange 25b containing holes 26. The brush holder may be secured to the motor by means of rivets or bolts through the holes 26 in the customary manner.

The spring 16 is prestressed in such a manner that it takes a cross-sectional camber when any portion is unwound. This camber tends to cause the unwound portion to press the brush 11 tightly against the brush holder 10 and, thus, aid in preventing the brush from chattering. A slot opening 27 is cut in the movable base member 18 to allow the cambered spring to sink slightly into the removable base member.

The outer end of the brush 11 is sloped as shown at 11a in Fig. 2. Thus, the coiled volute 30 tends to urge the brush toward the inner surface of the side of the casing 10 that is opposite to the base plate 18 and also tends to prevent chattering.

The casing 10 is constructed in an upper and lower section. These sections are fimly held together by rivets 28.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claim.

I claim:

A brush holder for a motor having a commutator and a brush, comprising: a brush casing; a removable base member positioned in said casing at one side thereof; a brush movably positioned in said casing having one side adjacent to said base member, said casing having the brush receiving portion arranged substantially radially of said commutator and open at both ends and approximately corresponding in cross-sectional size and shape to the cross-sectional size and shape of said brush; a coil spring including an elongated metal strip having one end secured to said movable base member and lying therealong and its other end coiled into a self-rewinding volute, said volute bearing against the end of said brush opposite to the commutator to urge the brush toward said commutator, the end surface of the brush contacted by said volute being inclined toward said volute so that the pressure of the volute on said surface urges the brush toward the opposite side" of the casing from said base member; and a displaceable clip attached to the casing having a barrier part at the end of said casing opposite to the commutator for retaining said base member in said 5 casing.

References Cited in the file of this patent UNITED STATES PATENTS 

